Methods and apparatus for casting metal



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EDMUND Q. SYLVESTER M United States Patent Qfifice 3,032,841 Patented May 8, 1962 3,032,841 METHODS AND APPARATUS FOR CASTING METAL Edmund Q. Sylvester, 490 College Road, Lake Forest, Ill. Filed Jan. 13, 195$, Ser. No. 708,558 14 Claims. (Cl. Z269) This invention relates to the casting of metals to produce ingots, bars, and blanks of a variety of shapes, as well as finished and semi-finished products. More particularly, the invention relates to improvements in methods and apparatus for the bottom pouring of metal into molds with the aid of superatmospheric and/ or subatmospheric pressures for effecting flow of molten metal from a reservoir into the molds.

Numerous attempts have been made heretofore to provide commercially practical methods and apparatus of the general character described above, but such attempts have been beset by many difficulties which have prevented or substantially limited their commercial success. Some of these attempts have enjoyed a measure of success in casting low melting metals and alloys with which premature freezing can readily be avoided, or in casting relatively small articles from a relatively small reservoir of molten metal. The difiiculties which have so limited the success of prior methods and apparatus of this general character for the most part, have long been recognized in the art but have resisted commercially practical solutions. The nature of many of these difficulties will appear in the course of the following description of the solutions provided by the present invention.

A general object of the present invention is to provide methods and apparatus of the foregoing character which are capable of economical use throughout a large part of the metal casting industry, and particularly in the casting of iron, steel, and other relatively high melting metals and alloys into large and small articles of unfinished, semi-finished, and fully finished character.

Another general object of the invention is to provide methods and apparatus of the foregoing character which are capable of producing a higher percentage of more nearly perfect castings, thereby eliminating a large part of the costly rejects and repairs heretofore encountered in the industry.

Another general object of the invention is to provide methods and apparatus of the foregoing character which are adapted to the pouring of bars, slabs, tubular blanks, structural shapes, and the like in a steel manufacturing plant, with various economies compared to present practices in the steel manufacturing and fabricating industries, such as reducing or eliminating the large scale losses that result during the reduction of ingots into shapes of smaller cross-section, reducing or eliminating the costly need for the cropping of blooms, slabs, billets, and the like, and eliminating the need for expensive blooming mills, slabbing mills, billeting mills, and other primary mills customarily used to convert ingots into rough rolled steel shapes for subsequent rolling, forging, and drawing into finished products.

More specific objects of the invention, among others which will appear hereinafter, are to perfect methods and apparatus for the bottom pouring of metal castings. with the aid of a controlled pressure differential, for effecting metal flow so as to eliminate the freezing of metal in a pouring spout or conduit prior to completion of the pouring operations; to enable the metal in a ladle or other reservoir to be completely exhausted at the conclusion of the pouring operations; to facilitate and reduce the cost of handling the molten metal between the furnace in which it is produced and the molds into which it is cast; to enable the efficient and economical pouring of steel in a steel producing mill to directly produce semi-finished or even finished products, thus eliminating intermediate metal working operations heretofore customary in the industry; to reduce the amount of scrap which is inevitably produced and must be recovered in the economical conversion of molten iron and steel into semifinished or finished articles, and to eliminate various costly scrap producing and recovery operations which have heretofore been considered essential parts of conventional processes; to make possible the use of permanent molds in the casting of a greater variety of articles, with consequent mold economies, while producing more nearly perfect castings having superior surface finishes; to increase the rate of production of castings which can be achieved with a given capital investment; and to eliminate or minimize numerous technical problems which have heretofore prevented the widespread use of pressure and/or vacuum types of bottom pouring techniques in the iron and steel industry.

The present invention involves various improvements over, and is to be particularly distinguished from the inventions of my prior United States Patents Nos. 2,792,606 and 2,794,224. In accordance with those prior patents, molten metal is forced out of a ladle, by gas pressure, through a refractory pouring spout or conduit which extends upwardly through a sealed cover for the ladle and downwardly into the bath of molten metal in the ladle to a point adjacent but short of the bottom thereof. Insertion of the refractory pouring spout into the molten metal in the ladle while applying the cover to the ladle has involved various operational and mechanical difficulties. Also, because the open lower end of the spout had to be spaced above the bottom of the ladle, it has not been possible to empty the ladle through the spout by gas pressure, and this has presented additional operating problems. Thus, while the basic invention of those prior patents is presently in successful commercial use in the manufacture of cast steel railroad car wheels, for which it was primarily developed, it has not yet proved attractive for more general application to the casting of high melting point metals such as iron and steel. Thus, a further object of the present invention is to eliminate the difliculties and problems inherent in the process of my said prior patents.

A principal feature of the present invention by which the various objects of the invention are accomplished involves the withdrawal of molten metal from the bottom of a ladle or other reservoir into at least one separable, upwardly extending, pouring spout or conduit of inexpensive construction, and using a pressure differential to effect a controlled upward flow of molten metal through this spout or conduit into the bottom of a separable mold or the bottoms of a separable battery of molds. In this manner clean metal can be supplied to the mold or molds until the reservoir is substantially empty of molten metal, and substantially the entire unused residue of metal may be confined to the separable, inexpensive spout or conduit, which may then be economically scrapped for recovery of the small residue of solidified metal remaining therein.

Another important feature of the invention comprises unique methods and apparatus for initiating the flow of molten metal from a bottom opening of a ladle or the like into one or more separable pouring spouts of the character mentioned above.

Another important feature of the invention comprises unique methods and apparatus for feeding molten metal from the upper end of an upwardly extending pouring spout or conduit into separable molds so as to effect rapid but non-turbulent flow into the mold or molds.

Still another important feature of the invention comprises unique methods and apparatus for sequentially connecting the bottoms of a series of molds in communication with the upper end of the upwardly extending pouring spout or conduit so that one after another of the molds may be filled until the supply of molten metal has been exhausted from the supply reservoir, these last mentioned methods and apparatus including any of a variety of special methods and devices for retaining metal in each mold during its disconnection from the pouring spout or conduit while the metal in the mold is still entirely or largely in a molten condition.

Still other important but more specific featurm of the invention comprise: novel molds and methods of manipulating them for producing articles of various sizes and shapes from a particular reservoir and pouring spout setup; novel ladle designs and methods of manipulating them and supplying air pressure thereto for initiating and controlling the flow of metal therefrom; and novel overall plant layouts and operating procedures for efiicient u-tilization of the other features of the invention.

The foregoing objects, advantages, and features of the invention will be elaborated upon and more fully explained and illustrated in the course of the following detailed description of various embodiments thereof, taken in conjunction with the accompanying drawings.

1n the drawings:

FIGURE 1 is a somewhat diagrammatic, exploded view, in vertical section, of a simple form of ladle, pouring spout, and mold for use in carrying out the present invention.

FIG. 2 is a schematic plan view of a plant layout for making and pouring molten metal in accordance with the invention.

PEG. 3 is a vertical section of another alternative form of ladle, pouring spout, and mold connected in cooperating relationship in accordance with the invention.

FIG. 4 is an enlarged, fragmentary, vertical section of the ladle of FIG. 3 with means applied thereto for holding a bottom stopper in place while pouring molten metal into the ladle.

FIG. 5 is a vertical section of still another form of ladle and pouring spout assembled in cooperating r'ela-" tionship in accordance with the invention.

FIG. 6 is a vertical section of a generally similar assembly in which a ladle communicates with a plurality of pouring spouts arranged about the ladle, the ladle and multiple spout assembly being mounted on a truck for movement from one set of prepositioned molds to another for filling the same until the molten metal in the ladle has been exhausted.

FIG. 7 is a fragmentary, horizontal, sectional view of the array of spouts constituting a part of the assembly of FIG. 6, the section being taken as indicated by the line 7--7 of FIG. 6.

FIG. 8 is an enlarged, fragmentary, sectional view similar to FIG. 6 showing the ladle and pouring spout relationship while the filled ladle is in the process of being lowered into communication with the pouring spout, and showing the ladle stopper seated in the bottom opening of the ladle just prior to its being automatically displaced during the final stage of lowering the ladle onto the spout assembly.

FIG. 9 is a fragmentary vertical section of a metal pouring spout and mold assembly, the view being taken as indicated by the line 9-9 of FIG. 10 and showing the upper, metal-feeding end of a pouring spout after the spout has been placed in communication with a plurality or battery of separable molds to be filled thereby, such communication being established through a special, closable, gate structure that is separable from the spout and from the plurality of molds to be fed and closed thereby.

FIG. 10 is a plan view of the gate structure of FIG. 9 with the several molds in place thereon.

FIG. 11 is a vertical section of a special mold and core arrangement for casting tubular members, the mold and core arrangement being adapted to be used with a plurality of like molds and cores in combination with the gate 4 structure of FIGS. 9 and 10, a portion of the gate structure also being shown in vertical section, the section being taken as indicated by the line 11-11 of FIG. 10.

FIG. 12 is an enlarged vertical section of the mold of FIG. 11, but with a modified core disposed therein and shown in part in vertical section, a portion of the associated gate structure again being shown in its operative relationship with the mold and core.

FIG. 13 is a vertical section of still another assembly in which a ladle communicates with any desired number of pouring spouts, with modified means for placing the ladle in communication with the spout or spouts and for maintaining a controlled pressure on the molten metal in the ladle during the pouring operation.

Referring first to FIG. 1, a refractory lined, steel encased ladle 1 is shown separated fro-m a refractory lined, steel encased spout 2 with which it is to be associated in use. The ladle 1 has a bottom pouring opening 3 and a refractory lined cover 4 which may be removably seated on an annular sealing gasket 5 and clamped tight by a plurality of clamps 6 (only one being shown) circumferentially spaced about the ladle. The cover 4 is provided with a compressed gas inlet fitting 7 to which a source (not shown) of compressed gasor inert gas may be connected through a three-way valve 8 for supplying gas under pressure to the ladle. The valve 8 may also have a gas exhaust conduit 9 connected thereto so that gas pressure in the ladle may be quickly relieved by manipulatin the valve. The source of compressed gas should include any suitable, variable pressure regulator with appropriate programming controls (also not shown) for progressively applying an accurately controlled gas pressure to the ladle.

The bottom pouring opening 3 of the ladle 1 is provided with a nipple 10 shaped to fit in sealed relationship with a lip 11 on the lower end of the spout 2 and to bequickly removed therefrom. Any desired brackets or clamps (not shown) may be used to removably clamp the spout 2 in communication with the ladle 1, the nipple- 10 and lip 11 being adapted to be interfitted to prevent leakage of molten metal through the joint. The freezing of molten metal as it may work its way into this joint will aid in making the joint tight against any continuing. leakage.

The lower end of the spout 2 may be provided with any desired form of simple refractory valve structure 12; for temporarily closing the spout to flow of molten metal therethrough. As shown, this valve may include a slidable plate 13 of graphite or the like which may be raised by means of a connected stem 14 until the bore of the spout is unobstructed.

The spout 2 extends upwardly to an upper open end adapted to removably receive a mold assembly, including a mold 15 and a closable refractory gate structure 16. As shown, the gate structure 16 may comprise a tubular body adapted to be closed by an apertured sliding plate 17, as indicated by the arrow 18, to position an imperforate portion of the plate across the bore of gate structure for closing the bore.

The mold 15 may be of any desired form having a bottom opening disposed in communication with the spout 2 through the gate structure 16. If desired, the mold 15 and gate structure 16 may be preassembled and suitably bolted or clamped together for placement over the open upper end of the spout 2. As explained below, a plurality of such mold and gate structure assemblies may be preassembled for placement one after another in communication with the spout 2 for filling each of the molds.

To use the apparatus of FIG. 1 for casting molten metal, such as iron or steel, the spout 2 is connected securely to the ladle 1, with or without the mold 15 and gate structure 16 in place on the upper end of the spout. With the cover 4 of the ladle removed, hot molten metal is poured into the ladle until it is substantially full. Thereupon, the cover 4 is clamped in place, the compressed gas line is connected to the fitting 7, and the valve 12 is opened to permit flow of molten metal into the spout 2. With a mold 15 and gate structure 16 in place on the upper end of the spout and the gate plate 17 retracted as shown, gas pressure is progressively built up in the ladle 1. This causes the molten metal to rise upwardly in the spout 2 through the gate structure 16 and into the mold 15. The gas pressure in the ladle is progressively increased until the molten metal rises to the top of the mold. The gate plate 17 is then moved to close the bore thereof and retain the molten metal in the mold. At the same time, or immediately thereafter, the valve 8 is manipulated to relieve the gas pressure in the ladle and permit the molten metal level in the spout 2 to drop below the upper end thereof. The inherent porosity of refractory materials and air leakage through the joint between the spout and gate structure quickly relieve any vacuum that might otherwise be created adjacent the gate plate 17 and restrain dropping of the molten metal level in the spout.

The filled mold 15 and attached gate structure 16 are then removed as a unit and replaced with a similar empty mold and gate structure. Pressure is then again applied to the ladle, and the procedure described is repeated over and over until the ladle 1 has been substantially emptied. At this point, a small residue of molten metal will be left in the spout and will quickly freeze therein, The spout is then disconnected from the ladle and replaced with a new spout so that the ladle may be refilled and the above described process repeated.

The spout structure 2 may be made up of separable steel casing sections and separable refractory lining sections in any of a variety of ways so that the refractory lining of the steel casing may be readily removed and replaced at small cost. The removed, refractory, spout lining sections in which any appreciable amount of so lidified metal residue remains may be broken up for recovery of this metal, which may be remelted for reuse in the process. Only arelatively small residue of metal will remain and solidify in the ladle portion of the apparauts and may be cleaned out as conditions may require before reusing the ladle. Thus, only the inexpensive refractory lining of the lower portion of the spout will normally have to be scrapped and replaced each time a ladle has been emptied.

The advantages of the invention in practice are indicated by the use of the invention as diagrammatically illustrated in FIG. 2. Any conventional type of smelting furnace 25, such as an open hearth or electric steel making furnace, a blast furnace for making pig iron or ferro alloys, a Bessemer type furnace, or the like, may be associated with the casting apparatus of the invention for directly producing castings of desired shapes without first producing intermediate cast shapes, such as pigs or ingots. The furnace 25 may be tapped to discharge its contents through a spout 26 directly into a ladle 27, which may be of the type shown in FIG. 1, for example. The ladle may have an upwardly directed pouring spout 28 previously connected thereto in the manner and for the pur poses described above, and the ladle and spout assembly may be carried to the furnace on a car 29 adapted to travel about a predetermined closed path on a pair of tracks 30. When the ladle has been filled and quickly closed to retain the sensible heat of the molten metal, the car 29 is moved along the tracks 30 to one after another of a plurality of mold filling stations 31, 32, 33, and 34. At each of the mold filling stations, one or a plurality of molds and a closable gate therefor (not shown) may be prepositioned for being placed in communication with the open upper end of the ladle spout 28, and a compressed gas source (not shown) may also be provided at each of these stations for connection to the ladle to discharge molten metal therefrom,

Molds are filled at one or a succession of such mold stations until the ladle 27 is substantially empty, in the manner described above. Thereupon, the car 29 is moved along the tracks 30 to a station 35 where the spout 26 is removed from the ladle and disassembled as required to recover any residue of solidified metal therefrom. As indicated by the arrow 36, the recovered metal may be moved into the furnace 25 for remclting or reuse.

From the spout removal station 35, the car 29 is moved along the tracks 30 to a final station 37 where any necessary operations for reconditioning the ladle 27 may be performed, including the connection of a new spout 26. The ladle is then ready to be moved on the car 29 around the same closed path for repeating the foregoing series of steps. Obviously, any desired number of additional ladle-carrying cars may be used in series on the same set of tracks and be sent one after another about the closed path to adjust the total ladle capacity to the capacity of the furnace 25 to be served, and to insure continuity of operation. Similarly, any number of mold filling stations may be employed, in series or parallel arrays, to adjust the total mold capacity to the capacity of both the ladle or ladles and the furnace.

In the light of the foregoing description of the invention, with particular reference to certain basic equipment requirements diagrammatically shown in FIG. 1, various refinements and modifications of such basic equipment will now be described. Depending upon the products to be cast, upon the metal or alloy to be used, upon the volume of production desired, and, to a considerable degree, upon engineering design preferences and future economic considerations, any of these and numerous additional apparatus variations and techniques may be best suited for meeting specific needs in the metal fabricating arts. It is to be understood that the particular forms of apparatus and operating techniques selected here for illustrative purposes are disclosed merely as examples of many possible alternatives within the scope of the invention which will occur to those skilled in the art.

Referring to FIG. 3, a refractory lined ladle 41 is shown having a dished bottom 42 and a bottom opening 43 centrally disposed therein to facilitate exhausting the ladle of molten metal. The metal casing 44 of the ladle is provided with an upper hollow rim 45 which provides a substantial, non-porous seating surface for a sealing gasket 46 and also forms an annular chamber 47 through which a cooling fluid may be circulated to protect the gasket 46 from the effects of excessive heat. Handles 48 may be provided on a refractory lined cover 49 for receiving crane hooks or the like which may be required for removing and replacing the cover. In place of a valve on an associated spout structure, as in FIG. 1, a refractory stopper 50 may be seated in the opening 43 to retain molten metal in the ladle, the stopper 50 having a stem 51 which may be used to hold the stopper in place, as hereinafter described. Thus, the ladle 41 may also be substantially filled with molten metal 52, before connecting a removable spout structure thereto. In other respects, the ladle 41 is essentially the same in structure and function as the ladle 1 of FIG. 1.

When the ladle 41 has been charged with molten metal and closed by the cover 49, the ladle may be lowered by a crane into engagement with a refractory lined steel spout structure 55, as shown. In this case, the lower end of the spout structure terminates in an upturned open mouth structure 56 shaped to seat in sealing engagement with a recess in the bottom of the ladle. When connecting the filled ladle 41 to the spout structure 55, the upper end of the spout structure may .also be open and unobstructed, and the gas conduit 57 through the ladle cover 49 may be open for gas exhaust from the ladle. By placing any suitable adapter on the end of another compressed air conduit (not shown) in communication with the upper open end of the spout 55, a blast of air under pressure may be suddenly discharged into the, upper end of the spout and through the spout to raise the stopper 50 off of its seat. The stopper 50 may be made of any of many suitable refractories of substantially less density than the molten metal 52, so that the stopper will fioat to the surface of the molten metal when displaced a substantial distance from its seat by air pressure. This places the ladle in free-flowing communication with the spout, whereby the molten metal rises in the spout to the same level existing in the ladle.

The above described assembly of FIG. 3 is then ready for a mold 58 and associated gate structure 59 to be lowered into communication with the upper end of the spout as shown. The body of the gate structure 59 may be made of any desired structural metal with a bore that is lined with graphite 61 or other refractory material. An apertured closure plate 62 may be slidably mounted in the body of the gate structure to close the bore of the gate structure when the plate is pushed inwardly for that purpose. An air cylinder 63 or the like may be suitably mounted on the gate structure for sliding the closure plate 62 inwardly after the mold 58 has been filled. The mold 58 may be bolted or clamped to the gate structure 59 in any desired manner, and the mold and gate structure assembly may thus be lowered into place as a unitary assembly.

When the filled and closed ladle 41, spout structure 55, and mold and gate structure 58 and 59 have been assembled as described, the mold 58 may be filled by applying gas pressure to the conduit 57 as described in connection with FIG. 1. When the mold 58 has been filled, the cylinder 63 is actuated to close the gate for retaining molten metal in the mold, the gas pressure at the conduit 57 may be relieved, and the filled mold .and gate structure may be removed and replaced with another, the series of mold filling operations being repeated until the ladle 41 is substantially empty.

Referring next to FIG. 4, a simple arrangement is shown for holding the stopper 50 securely in place during filling of the ladle 41. The stem 51 of the stopper is provided with a key-receiving opening 64. A washer 65 is seated against the bottom of the ladle and the stem '1 of the stopper is passed therethrough. A key 66, having a cable 67 attached thereto, is passed through the opening 64 in the stem 51 to hold the stopper and Washer in place until the ladle is filled. With the stopper then held in place by the pressure of molten metal in the ladle, the key may be safely jerked out by the cable 67, permitting the washer 65 to fall off and leave the stopper free to be displaced by air pressure as described above. Obviously, a variety of snap-acting clamps or the like may be similarly employed to temporarily hold the stopper securely in place during filling of the ladle 41.

Referring next to FIG. 5, another form of ladle 71 is shown that is generally similar to the ladle 41 of FIG. 3, but is designed to be assembled with a modified spout and valve structure 72 before being filled with molten metal. The spout structure 7'2 is secured to the ladle 71 by bolted flanges 73 formed on the steel casings of the ladle and spout structure.

The assembly of the ladle 71 and spout structure 72 may be mounted on a support 74 which may be stationary or portable, as desired, according to whether this assembly is to have molds delivered to it, one after another, or is to be moved from one to another of a series of mold setups.

The ladle 71 may have a bottom shaped to slope from three sides toward a low point in the center of the fourth side at the mouth of a bottom outlet nipple 75. Within the nipple 75, a seat 76 is provided for a stopper 77. A rod 78 projects outwardly through a refractory block 79 and through the spout casing into a pneumatic cylinder 80 also mounted on the support 7 4. A piston (not shown) in the cylinder 80 is pnuematically operated, first in a direction to hold the stopper 77 in place against the seat 76 and then in the opposite direction to withdraw the stopper from the ladle outlet to a position entirely within a recess 81 within the spout structure. After the ladle 71 is substantially filled with molten metal 82, the stopper 77 is withdrawn pneumatically, as described, and the assembly is then used in essentially the same manner as the similar assembly of FIG. 3.

Referring next to FIGS. 6, 7, and 8, an arrangement is shown for automatically displacing a stopper in the bottom outlet opening of a ladle while connecting the ladle in communication, simultaneously, with a plurality of upwardly extending mold feeding spouts. In this case, the ladle 91 is substantially the same as the ladle 41 of FIG. 3. The only significant differences are the provision of a depending annular lip 92 about a central bottom opening 93 of the ladle and the provision of a longer stem 94 on a refractory stopper 95. The stopper 95 may be temporarily held in place during filling of the ladle 91 by a removable washer and key, as described above and illustrated in FIG. 4, or by any other form of releasable lock, clamp, or the like. I

The spout structure of FIG. 6, shown in more detail in FIGS. 8 and 9, includes a central mouth 96 adapted to receive the depending lip 92 of the ladle as the ladle is lowered to engage a seat 97 on the spout structure. As the lip 92 enters the mouth 96 of the spout structure, the stem 94 of the stopper 95 engages the bottom of the spout structure. Further lowering of the ladle to seat it on the spout structure raises the stopper, as shown in FIG. 6, so that molten metal may flow from the ladle into the spout structure. As soon as the suction effect of this downward flow of molten metal around the stopper 95 diminishes, the relatively low density of the stopper will permit it to float to the surface of the molten metal, as does the stopper in the ladle of FIG. 3.

The spout structure of FIGS. 6, 7, and 8 may include a plurality of branches 98 radiating from the central mouth 96, four such branches 98 being shown in this instance, although a greater or lesser number may obviously be employed. The plurality of branches 98 may be identical, each including a horizontal portion and an upturned vertical portion terminating in an upper open end 99 for receiving a suitable mold and gate structure to be fed thereby. As will be apparent, placing of the filled ladle 91 in communication with the mouth 96 of the spout structure while displacing the stopper 95 will cause molten metal to flow into each spout branch 98 and to rise upwardly therein to the level of molten metal in the ladle 91.

By placing a mold or a battery of molds and an associated gate structure in communication with the upper open end of each spout branch 98, and by applying gas pressure to the ladle as previously described, all of the molds may be simultaneously filled from the ladle 91. The ladle and spout assembly may conveniently be mounted on a platform carried on a portable truck 100 and adapted to be hydraulically raised and lowered under each of a series of prepositioned multiple mold assemblies for filling the molds of one such assembly after another until the ladle is empty.

Referring next to FIGS. 9 and 10, a modified gate structure and multiple mold assembly is shown with a plurality of molds 101 communcating with the open upper end of a pouring spout 102 through the interposed gate structure 103. As shown, the gate structure 103 may include a steel case 104 and a funnel shaped refractory lining 105 defining a flared upward extension 106 of the bore 107 of the spout structure 102. The upper part of the gate structure 103- may include a flanged cover plate 108, which may suitably be made of copper, for example, to provide high heat conductivity and rapid freezing of molten metal in this region. The cover plate 108 may have a central aperture formed therein to slidably receive a shaft 109 carrying a gate closing refractory stopper 110 on the lower end thereof. By forcing the shaft 109 downwardly, the stopper 110 may be seated in the throat of the gate bore 106 to close the same.

The flanged cover plate 108 of the gate structure 103 may also have a plurality of frusto-conical apertures formed therein (four being shown) in which a corresponding plurality of refractory plugs 111 are seated. Each plug 111 may have a plurality of relatively small diameter passageways 112 (for being shown) formed therein for permitting restricted streams of molten metal to flow upwardly therethrough from the bore 106 of the gate structure into the molds 101.

Each mold 101 may be provided with a pair of locating ears 113 and 114. The ears 113 may have round apertures formed therethrough for receiving locating pins or studs 115 fixed in the flanged cover plate 108. The ears 114 may have elongated slots formed therein which extend radially of the mold to receive additional locating pins or studs 115, thus permitting thermal expansion and contraction of the molds 101 relative to the cover plate 108 without breaking the pins 115, while still positioning the molds relative to the apertured plugs 111.

With the stopper 110 in its raised position, molten metal may be forced to flow upwardly from the spout 102, through the gate structure 103 and the passageways 112 of the plugs 111 and into the molds 101. The flow of metal into the molds 101 may be controlled by regulating the gas pressure used in an associated ladle to force the metal upwardly in the spout 101, and also by using appropriate size passageways 112 in the gate plugs 111, in order to provide smooth, non-turbulent flow of molten metal into the bottoms of the molds 101. In this way, the known advantages of bottom pouring may be obtained to the optimum degree, and castings of a uniformly high quality may readily be produced.

When the molds 101 have been filled, the shaft 109 may be forced downwardly to seat the stopper 110 in the throat of the gate bore 106, thus closing the gate to retain molten metal in the molds. The molten metal in the spout 102 is then permitted to drop by relieving the gas pressure in the associated ladle, and the entire gate structure and mold assembly is separated as a unit from the spout structure. Since the freezing of molten metal will occur more quickly in the small passageways 112 and around the lower portion of the mold than in the bore 106 of the gate structure, the molds 101 and associated gate plugs 111 will normally pull together away from the gate cover plate 108 when separating the molds from the gate structure. This is most easily done as soon as the gate structure is separated from the spout structure. Whether or not the plug passageways 112 are frozen completely shut at that time, they will be at least largely restricted by the quick freezing of metal therein. This condition will quickly occur to such a degree that the viscosity and surface tension of the cooling metal in the mold will prevent any loss of this metal through the passageways 112 during separation of the molds from the gate structure, even though metal immediately above and below the passageways 112 is still in a molten condition.

As indicated above, when one gate structure and mold assembly has been separated from the spout structure 102, a similar assembly may immediately be placed in communication with the spout for repeating the described mold-filling operations.

Referring now to FIG. 11, the fragmentarily illustrated gate structure 108 may be identical with the gate structure of FIGS. 9 and 10, and the mold casing 101 may .also be the same and be positioned on the gate structure in the same manner by mold ears 113 and 114 and gate structure pins 115. A modified gate plug 111a having passageways 112a therethrough may be similar to the corresponding parts of FIGS. 9 and 10 except for the provision of a central core-positioning recess 117 in the plug 111a. Depending upon the height of the mold 101 relative to its diameter, it may be necessary to steady it on the gate structure 103 by means of a suitable spider or framework 118. A hot top 119 is preferably provided on the mold 101 and may also be steadied by the spider or framework 118. Inside the mold 101, a central core 120 may be disposed and centered with its lower end held in the central recess 117 of the gate plug 111a. The upper end of the core may be held centered in the mold by wiring it to the hot top 119 or by any kind of simple bracket or the like (not shown), as will be clearly understood by those skilled in the art. In the arrangement of FIG. 11, the core 120 may be made of any conventional core material .so that it may be removed from the tubular casting that will be formed when metal is fed into the bottom of the mold through the plug passageways 1120.

By using the mold arrangement of FIG. 11, it is a simple matter to make high quality tubular castings. Such tubular castings may constitute finished or semifinished products for various uses. Alternatively, they may be used as blanks to be drawn into longer, thinner walled, seamless tubes in a tube mill, without the necessity of first piercing solid blanks which are now conventionally used in the drawing of seamless tubes.

FIG. 12 illustrates, on an enlarged scale, how the mold core of FIG. 11 may be modified to directly cast tubes of ordinary iron or steel with'a stainless steel lining. Except for the mold core 130, all parts of the assembly of FIG. 12 may be identical with the parts of the assembly of FIG. 11, as indicated by the corresponding reference characters in these two figures of drawings.

The mold core in FIG. 12 may comprise an iron or steel rod 131 extending through the center of the mold cavity and surrounded by a thin stainless steel tube 132, with an annular layer 133 of a bonded core sand or the like disposed between the central rod 131 and the outer tube 132. In order to facilitate the escape of entrapped air and moisture from the layer 133 of core sand during the casting operation, an upper core piece 134, made entirely of bonded core sand, may be positioned on top of the composite core member just described. This upper, porous core piece provides passageways therethrough for the escape of such air and moisture after molten metal has risen to this elevation in the mold.

When metal is cast in the mold of FIG. 12 around the composite core 130, it will bond to the thin stainless steel tube 132, since this thin tube will have little chilling effect on the molten metal. After the casting has been removed from the mold 101, the central rod 131 and layer of core sand 133 may be easily removed to leave a stainless steel lined, tubular casting. Such a stainless lined tube may also be drawn down on a tube mill, if desired, to produce longer lengths of stainless lined, thin wall tubing.

In FIGS. 1, 3, 5, and 6, ladles have been shown which serve to hold the molten metal to be poured and also to hold the gas pressure utilized in forcing molten metal from the ladle into a mold or molds at a higher elevation. It is contemplated that gas pressures as great as 100 to pounds per square inch may be utilized in some instances in order to force metal to substantial heights, as in the casting of elongated bars or hollow tubes. Utilizing the ladle as a pressure vessel, with such high gas pressures superimposed upon the hydrostatic pressure of molten metal, is undesirable. However, this may readily be avoided by closing the ladle and applying pressure thereto in a different manner as illustrated in FIG. 13, for example. Obviously, this or a similar manner of closing and applying pressure to the ladle may be utilized with the various types of ladles and pouring techniques shown in the other figures of the drawings and described above.

Referring to FIG. 13, the ladle 141 may be generally similar to the ladles of FIGS. 3 and 6 and may be equipped with a similar bottom outlet stopper 142 having an elongated stern 143 for initially securing the stopper in place and subsequently displacing it in the same general manner shown in FIGS. 4 and 8. In this instance, a multiple spout construction 144 is shown, which is generally similar to that shown in FIGS. 6, 7, and 8. The central mouth 146 of this spout structure 144 projects aosaear 1 1 upwardly for engaging about the central, bottom opening 147 of the ladle 141.

Superimposed over the radiating, horizontal legs 148 of the spout structure 144 is a heavy, rigid, steel plate 149 of annular configuration, which may be partly or largely supported at opposite sides of the radiating spout legs by any suitable structure (not shown) so as to carry the weight of a filled ladle and its cover structure without crushing the radiating spout legs. The inner periphery of the plate 149 is sealed at 150 about the mouth 146 of the spout structure so as to be capable of withstanding the gas pressure to be applied in and about the ladle 141.

A circular array of any desired number of hydraulic rams 151 may be mounted on the plate 149 for initially supporting the ladle 141 spaced upwardly out of engagement with the mouth 146 of the spout structure, and with the lower end of the stopper stem 143 spaced upwardly out of engagement with the bottom of the spout structure 144. The outer periphery of the plate 149 projects radially outwardly beyond the ladle 141 to provide a seat for a rigid, steel bell 152 enclosing the ladle 141.

The lower end of the bell 152 may be flanged and recessed to hold an annular sealing gasket 153 adapted to provide a gas pressure seal between the bell and the plate 149. The top of the bell may have a gas pressure conduit 154 connected thereto for intermittently supplying gas under pressure into the bell and relieving the pressure again during the pressure pouring of molten metal as hereinbefore described. Eyes 156 may be provided on the bell for lifting and lowering it with a crane. Also, a circular array of any number of hydraulic rams 157, mounted on any suitable superstructure 158, may also be provided to hold the bell 152 firmly seated on the plate 149 as pressure is built up in the bell. The. superstructure 158 is preferably movable horizontally out of the way to one side of the ladle to permit the bell 152 to be conveniently moved into place and removed again.

When the ladle 141 has been filled with molten metal 160, the ladle is lowered onto the hydraulic rams 151 in their raised condition. The bell 152 is then lowered into place and the hydraulic rams 157 are actuated to apply a downward force on the bell. Thereupon the hydraulic rams 151 are retracted to lower the ladle 141 into communication with the spout structure 144 while displacing the stopper 142, as is done when seating the ladle 91 on the spout structure of FIG. 6. The apparatus of FIG. 13 is then operated in the same manner as the apparatus of FIG. 6 for forcing metal through each vertical leg of the spout structure into molds placed in communication therewith until the. ladle 141 is exhausted.

To illustrate still another form of removable mold that is particularly adapted for use with the pouring ap paratus of the invention, a mold 165 is shown in place on the upper end of one of the spout legs in the apparatus of FIG. 13. The mold 165 may include any desired form of closable gate structure 166 with a separable hollow mold body 167 superimposed thereon in communication therewith. As shown at 168, the hollow interior of the mold body 167 may be rectangular or square in crosssection, for example, for molding bars of corresponding cross-section and any desired length. Although the upwardly extending spout legs and the mold 165 are both indicated in the drawing as extending vertically, the outlet of the spout and the mold 165 connected thereto may be inclined to the vertical in order to reduce the vertical height to which metal must be forced in casting a bar of a given length. In this way, the pressure required in the bell 152 for filling the mold may be reduced.

The molds shown in FIGS. 11 and 12 are provided with open, refractory hot tops 119. If desired, in order to retard the cooling and solidification of metal in the upper end of a mold, a closed hot top of porous, molded, core sand or the like may be used, such as the hot top 169 in FIG. 13. The porosity of the hot top will permit tlie escape of air and gases therethrough as molten metal rises in the mold 165. When the mold is full, it may contact electrical conductor elements of any desired type in the hot top (not shown) to trip a circuit, terminate the pressure build-up in the ladle, and: initiate the closing of the gate 166 and the exhausting of gas through the conduit 154.

From the foregoing description of various forms of equipment and various operating techniques, it will be understood that the invention is susceptible to many detailed modifications according to the specific objectives to be accomplished. Uses for all of these variants of the invention and others which will occur to those skilled in the art are contemplated and are intended to be embraced by one or more of the appended claims. Those familiar with the art of metal casting, and particularly the art of casting relatively high melting point metals, such as iron and steel, will readily appreciate from the foregoing disclosure how the various objects and advantages of the invention may be achieved in practical commercial plant operations.

Having described my invention, I claim:

1. A method of casting metal from a reservoir of molten metal contained in a closed and sealed ladle having a bottom pouring opening, comprising placing said opening in free-flowing sealed communication with the lower end of a separable, upwardly extending, refractory, pouring conduit disposed externally of said reservoir for delivery of metal from the ladle to a mold, placing the upper end of the pouring conduit in sealed communication with the bottom of a separate mold, causing free flow of molten metal from the ladle into the pouring conduit, creating a pressure differential between surfaces of the molten metal within and outside of the ladle to cause continued flow of molten metal from the ladle into the pouring conduit and upwardly therethrough into the mold until the mold is full, relieving said pressure differential while preventing reverse flow of molten metal out of the mold in order to permit the molten metal level in the pouring conduit to descend below the upper end thereof, separating the filled mold from the pouring conduit, filling enough molds in the foregoing manner to substantially empty the ladle of molten metal, and finally separating the pouring conduit from the ladle to free the ladle for reuse.

2. A method of casting metal from a reservoir of molten metal contained in a closed and sealed ladle having a bottom pouring opening, comprising placing said opening in free-flowing sealed communication with the lower end of a separable, upwardly extending, refractory, pouring conduit disposed externally of said reservoir for delivery of metal from the ladle to a mold, placing the upper end of the pouring conduit in sealed communica tion with the bottom of a separate mold, causing free flow of molten metal from the ladle into the pouring conduit, creating a pressure differential between surfaces of the molten metal within and outside of the ladle to cause continued flow of molten metal from the ladle into the pouring conduit and upwardly therethrough into the mold until the mold is full, interrupting the flow of molten metal from the ladle into the pouring conduit while preventing reverse flow of molten metal out of the mold, separating the filled mold from the pouring conduit, filling enough molds in the foregoing manner to substantially empty the ladle of molten metal while leaving a residue thereof in the pouring conduit, and finally separating the pouring conduit from the ladle to free the ladle for reuse.

3. A method of casting metal from a reservoir of molten metal contained in a closed and sealed ladle having a bottom pouring opening, comprising closing said opening with a displaceable stopper, charging molten metal into the ladle, closing and sealing the ladle, placing said opening in sealed communication with the lower end of a separable, upwardly extending, refractory, pour- 13 ing conduit disposed externally of said reservoir for delivery of metal from the ladle to a mold, displacing said stopper to permit free flow of molten metal through said opening from the reservoir into the pouring conduit and upwardly therein toward the upper end thereof, placing the upper end of the pouring conduit in sealed communication with the bottom of a separate mold, creating a pressure differential between surfaces of the molten metal within and outside of the ladle to cause continued flow of molten metal from the ladle into the pouring conduit and upwardly therethrough into the mold until the mold is full, interrupting the flow of molten metal from the ladle into the pouring conduit while preventing reverse flow of molten metal out of the mold, separating the filled mold from the pouring conduit, filling enough molds in the foregoing manner to substantially empty the ladle of molten metal, and finally separating the pouring conduit from the ladle to free the ladle for reuse.

4. A method of casting metal according to claim 3 in which said mold is provided with a separable closure means operable to close the mold when it is full of molten metal, and the mold and closure means are removed as a unit while the flow of molten metal from the ladle into the pouring conduit is interrupted.

5. A method of casting metal according to claim 3 in which said mold is provided with a separable closure means operable to close the mold when it is full of molten metal, and the mold and closure means are removed as a unit while the flow of molten metal from the ladle into the pouring conduit is interrupted, whereupon additional similarly closable molds, one after another, are placed in communication with the upper end of the pouring conduit and are filled, closed, and removed in the same manner as the first until the molten metal in the ladle is substantially exhausted.

6. A method of casting metal according to claim 3 in which the bottoms of a plurality of separate molds are simultaneously placed in communication with the upper end of the pouring conduit and simultaneously receive molten metal therefrom, and a separable closure means is disposed between the upper end of said ouring conduit and said plurality of molds, and the closure means and plurality of molds are removed as a unit while the flow of molten metal from the ladle into the pouring conduit is interrupted.

7. Apparatus for casting metal comprising a refractorylined ladle having a removable cover and a bottom outlet opening, a separate, generally upright spout structure defining a refractory-lined pouring conduit having a lower open end and an upper outlet end, mating surfaces about the bottom outlet of the ladle exteriorly thereof and about the lower end of the spout structure, respectively, for removable engagement to place the pouring conduit in sealed communication with the bottom outlet of the ladle with the spout structure disposed entirely outside of the ladle, means for sealing the cover to the ladle for retaining gas under pressure therein, and means for introducing gas under a controlled pressure into the ladle adjacent the cover for forcing molten metal out of the ladle through the bottom opening thereof, into and through the spout, and out of the upper end of the spout, whereby the ladle can be substantially emptied of molten metal by gas pressure therein and the spout structure disconnected therefrom to free the ladle for reuse.

8. Apparatus according to claim 7 in which said spout structure includes means defining a plurality of generally vertically disposed pouring conduit branches extending upwardly from the lower open end of the spout structure for receiving molten metal therefrom, each of said branches having an upper outlet end and a separate hollow mold removably associated therewith for receiving molten metal therefrom through a bottom opening provided in the mold.

9. Apparatus for casting metal comprising a refractorylined ladle having a removable cover and a bottom outlet opening, a separate, generally upright spout structure defining a refractory-lined pouring conduit having a lower open end and an upper outlet end, mating surfaces about the bottom outlet of the ladle exteriorly thereof and about the lower end of the spout structure, respectively, for removable engagement to place the pouring conduit in sealed communication with the bottom outlet of the ladle with the spout structure disposed entirely outside of the ladle, means for sealing the cover to the ladle for re taining gas under pressure therein, means for introducing gas under a controlled pressure into the ladle adjacent the cover for forcing molten metal out of the ladle through the bottom opening thereof, into and through the spout, and out of the upper end of the spout whereby the ladle can be substantially emptied of molten metal and the spout structure disconnected therefrom, a separate hollow mold having a bottom inlet opening, and mating surfaces about the bottom inlet of the mold and the upper outlet end of the spout, respectively, for removable engagement to place the spout in communication with the mold for supplying molten metal thereto in response to the introduction of gas under pressure into the ladle through said gas introducing means, and mold closure means associated with said mold and removable therewith from engagement with the spout for preventing reverse flow of molten metal from the mold upon its removal from the spout.

10. Apparatus for casting metal comprising a refractory-lined ladle having a removable cover and a bottom outlet opening, a displaceable stopper for the bottom Opening for temporarily retaining molten metal in the ladle, a separate, generally upright s-pout structure defining a refractory-lined pouring conduit having a lower open end and an upper outlet end, mating surfaces about the bottom outlet of the ladle exteriorly thereof and about the lower endof the spout structure, respectively, for removable engagement to place the pouring conduit in sealed communication with the bottom outlet of the ladle with the spout structure disposed entirely outside of the ladle, the upper outlet end of the spout, when said mating surfaces are so engaged, being disposed at least substantially as high as the maximum level to which molten metal may be contained in the ladle, means for sealing the cover to the ladle for retaining gas under pressure therein, and means for introducing gas under a controlled pressure into the ladle adjacent the cover for forcing molten metal out of the ladle through the bottom opening thereof, into and through the spout, and out of the upper end of the spout, whereby the ladle can be substantially emptied of molten metal by gas pressure therein and the spout structure disconnected therefrom to free the ladle for reuse.

11. Apparatus according to claim 10, including means for displacing said stopper after the spout has been placed in communicating engagement with said bottom opening of the ladle so as to permit free flow of molten metal from the bottom of the ladle into the spout and upwardly to a common level with molten metal in the ladle.

12. Apparatus according to claim 10, including means for displacing said stopper after the pouring conduit has been placed in communicating engagement with said bottom opening of the ladle so as to permit free flow of molten metal from the bottom of the ladle into the spout and upwardly to a common level with molten metal in the ladle, said means for displacing the stopper being separable from the ladle and carried by the spout structure.

13. Apparatus according to claim 10, including means for displacing said stopper after the spout has been placed in communicating engagement with said bottom opening of the ladle so as to permit free fiow of molten metal from the bottom of the ladle into the spout and upwardly to a common level with molten metal in the ladle, said means for displacing the stopper being carried by the ladle and extending therefrom for operating engagement by the spout structure when the latter is placed 15 in communicating engagement with the bottom opening of the ladle.

14. Apparatus for casting metal comprising a refractory-lined ladle having a removable cover and a bottom outlet opening, a separate, generally upright spout structure defining a refractory-lined pouring conduit having a lower open end and an upper outlet end, mating surfaces about the bottom outlet of the ladle exteriorly thereof and about the lower end of the spout structure, respectively, for removable engagement to place the pouring conduit in sealed communication with the bottom outlet of the ladle with the spout structure disposed entirely outside of the ladle, the upper outlet end of the spout, when said mating surfaces are so engaged, being disposed at least substantially as high as the maximum level to which molten metal may be contained in the ladle, means for sealing the cover to the ladle for retaining gas under pressure therein, means for introducing gas under a controlled variable pressure into the ladle adjacent the cover for forcing molten metal out of the ladle through the bottom opening thereof, into and through the spout, and out of the upper end of the spout whereby the ladle can be substantially emptied of molten metal by gas pressure therein and the spout structure disconnected therefrom to free the ladle for reuse, a separate hollow mold having a bottom inlet opening, and mating surfaces about the bottom inlet opening of the mold and the upper outlet end of the spout, respectively, for removable engagement to place the spout in communication with the mold for supplying molten metal thereto in response to the introduction of gas under pressure into the ladle through said gas introducing means, said hollow mold including a separable gate portion and the gate portion constituting a part of the bottom inlet of the mold, said gate portion including means operable for closing the bottom inlet opening of the mold to retain molten metal therein when gas pressure in the ladle is relieved and during subsequent removal of the mold from communicating engagement with the spout.

References Cited in the file of this patent UNITED STATES PATENTS 533,139 Potter Jan. 29, 1895 535,598 Potter Mar. 12, 1895 969,539 Kitchen Sept. 6, 1910 1,815,361 Morris July 21, 1931 2,618,477 Short Nov. 18, 1952 

